Documentation/feature: programatically-defined columns (from M2M objects, or another model)

[evildmp]

If it's possible to have programatically-defined columns, that should be documented.

I don't think it is, and so far I haven't been able to achieve it anyway, so I am not sure if it's even possible, but if I have a couple of pointers I'll be happy to write it up in the documentation.

Example use case: A child has a height. But Child.height alone perhaps isn't adequate, because children grow, so we might also have a model for Year, and a through model that allows us to record a Child's height for each Year. In the table we'd therefore want a column for each Year:

Child       1998  1999  2000   
----------------------------        
Eldest       155   162   170
Youngest      53    61    72
Middlest      80    91   103

It's possible to acquire both the Year column headings and data by looping over attributes in the template, but that negates much of the convenience that has been afforded.

[evildmp]

I came up with what seems like a good solution, https://stackoverflow.com/a/79447704/2422705.

Very briefly:

• subclass Column for a custom column with the queryset in its render()
• use get_table_kwargs() to add all the columns with extra_columns
• supply some data for the query to attrs in the call for the Column subclass

I think it would be useful to have this sort of use case documented more explicitly - would a pull request for that be welcomed?